Fluid handling – Processes
Reexamination Certificate
1998-11-19
2001-07-03
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Processes
C137S594000, C251S172000
Reexamination Certificate
active
06253778
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to valves for use in industrial processes.
More particularly, the invention relates to valves having multiple inlet and outlet ports.
More particularly the invention relates to a rotary valve having three or more ports.
BACKGROUND OF THE INVENTION
Many industrial processes require the use of valves for the cycling of flow streams. Such processes include drying, adsorption, gas sweetening and fume incineration. These processes generally employ some type of fluid moving equipment such as pumps, blowers and/or compressors as well as the numerous valves necessary to direct the gas flow to the appropriate vessel at the appropriate time.
The selection of appropriate valves for cyclic processes depends upon a number of criteria. These include flow, operating and sealing characteristics, port configuration, physical size, energy input (e.g. electrical, hydraulic or pneumatic) and cost. Because such processes typically employ relatively low pressures (e.g. in the range of 1 psia to 100 psia), large volumetric flows result. In such situations, it is therefore necessary to have an accompanying low pressure drop, on the order of 0.05 psi to 2 psi.
Valve operating characteristics include quick opening and closing times, on the order of 0.25 to 2 seconds. Sealing characteristics include the type of seal, the mating surfaces, and the power required to open and close the valve to prevent any leakage during the full-closed position. As to port configuration, it is noted that a majority of valves handle a single fluid, and consequently these have one port for entry of fluid and one port for exiting of fluid.
Multiples of this type of valve have long been used for the control of cyclic processes, as given their nature, numerous valves are required. It is necessary to interconnect these valves thus requiring extensive interconnecting piping. In order to maintain a low pressure drop with the use of dual valves, relatively large valve sizes are required (e.g. greater than 10 inches in diameter), resulting in relatively slow open/close times and high costs.
Kice, in U.S. Pat. No. 3,489,178 teaches a valve design with both inlet and outlet directions perpendicular to the axis of rotation. This design does not utilize a large portion of the outer diameter of the valve, thus requiring a valve of increased size and cost.
Tucker, in U.S. Pat. No. 2,312,941 teaches a valve having very small clearances to seal the ports having different pressures. This requires an oversized valve body at additional expense. Further, the inertia associated with the thick walled valve drum causes an increase in valve response time and consequently excessive operating costs.
Thus, there is a need in the art to improve valve design to more nearly meet all of the criteria for cyclic service.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to provide a valve design that is useful in cyclic processes.
It is a further object of the invention to provide a valve that has a relatively low pressure drop when used in low pressure applications.
It is a further object of the invention to provide a valve that is multi-ported so as to minimize the amount of piping required for cyclical processes.
SUMMARY OF THE INVENTION
The invention comprises a rotary valve having first and second inlet/outlet flow passages, as well as one or more (preferably between 6 and 8) flow ports. The valve has a plurality of positions simultaneously interconnecting the first and second flow passage to selected flow ports. Thus the valve in a first position may be adapted to connect a first or second flow passage and a first flow port and the valve in a second position may be adapted to connect a first or second flow passage and a second flow port. As is readily apparent, numerous positions are possible for connecting flow passages to flow ports, with the number increasing with the number of flow ports.
In a preferred embodiment, the valve has a housing and the flow ports are disposed on outer peripheral walls of the housing. The valve may further include an internal rotary plug that is rotatable about a longitudinal axis to move between the positions, and containing openings or passages to connect the flow passages to the flow ports.
The plug may be divided into two chambers within the valve, with one of the chambers corresponding to a first valve portion, and the other of the chambers corresponding to a second valve portion. Each of the chambers may be moved independently of each other, or may be connected to each other and moved together.
The valve may further include a movable seal between the housing and the internal plug member which is retractable to permit free movement of the plug between the positions.
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Kun Leslie Charles
Smolarek James
Follett Robert J.
Hepperle Stephen M.
Praxair Technology Inc.
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